Errors/Exceptions

Upon failure, an E_WARNING is emitted.

Notes

Note:

Note: In most Unix filesystems, a file is considered changed when its
inode data is changed; that is, when the permissions, owner, group, or
other metadata from the inode is updated. See also
filemtime() (which is what you want to use when you
want to create "Last Modified" footers on web pages) and
fileatime().

Note:

Note also that in some Unix texts the ctime of a file is referred to as
being the creation time of the file. This is wrong. There is no creation
time for Unix files in most Unix filesystems.

Note:

Note that time resolution may differ
from one file system to another.

Note: The results of this
function are cached. See clearstatcache() for
more details.

You should avoid feeding the function files without a path. This applies for filemtime() and possibly fileatime() as well. If you omit the path the command will fail with the warning "filectime(): stat failed for filename.php".